Smoking XL600

[amanda11270]

I picked up a pretty inexpensive XL600 (1985), its not the prettiest bike, however its the color scheme I always wanted in one of these.  The guy I bought it from told me it smokes and leaks oil from the exhaust, he stopped riding it about 4 years ago and got a xr650 because of this.

I cleaned the carbs today, chased the four years of sitting from the preventative maintenance and it starts easily, but it does smoke from the exhaust.  When I first started it, it smoked me out of my shop, its burning oil big time.  I ran it a little and it calmed down slightly, but it still smokes.  I did a compression test and got 130 PSI, but its probably a little more since its hard to get the tester tube tight down in the plug hole as I didnt want it to get stuck and not come out (its a bear to get to down there as my tester uses a adapter in this size).  

The guy I got the bike from, gave me a entire extra engine from a 86 model, he planned on fixing this bike, however I dont think he had the mechanical skills.  I can do this easily, but I was wondering if anyone could tell me if there is a more popular top end comonent that would cause this.  I have the piston and cylinder from the other motor, as well as the head, which all look real clean (the other engine is disassembled, I think he got it as individual parts), as well as as the valve cover and rocker assy. is also clean,  the other engine does not have a cam, but I can probably swap it with the existing motor's.

The bike seems to smoke more when I ride it harder, but its definitely oil and not a fuel issue.  It does start relatively easy though.

 

I was hoping someone could lead me towards either the head (valves) being the problem, or should I do the piston/cylinder too.  I can post pictures of the extra motors parts if that would help anyone in telling me if they would be worth using or not, I have worked on alot of vehicles, im just not as familiar with diagnosing this particular problem and would like to get it right the first time.

 

[Horri]

Is the other engine also an XL engine??..IMHO you can't/shouldn't attempt half arsed repairs when a bike smokes..You are better off doing a rebore and new piston/rings than trying hones etc.. Also..Replacing only the top valve seals is just too easy..If it was that simple the other owner would possibly have done it. Course you also have the possibility that it has a worn valve guide or one of the  seals below them is had it..Not much more I can add..those 3 areas are the smoke causes ..Definite new piston/rings and rebore and top valve seals..the guides and seals below are more of a maybe/,,how far do you want to go sort of thing..

 

Engine needs to come apart anyway..Then get the head and pour some thin flowing liquid in around the valve areas..If you leave it for a while and it weeps through into the combustion area you have some sort of valve/seal leak..still doesn't rule out the rebore etc imho..Cover bases,,

Edited August 4, 2014 by Horri

[Carter Pewterschmidt]

IMHO you can't/shouldn't attempt half arsed repairs when a bike smokes..You are better off doing a rebore and new piston/rings than trying hones etc.. 

Eh, if the guys got a parts motor and the cylinder and piston are actually good, why not swap the two over.  I mean, if it's just sitting there, you might as well make use of it if it's good.  That is, if it's needed.

 

Though I'd get the head rebuilt regardless,  These motors love eating valve guides, can have head warping/cracking, not to mention it's just an old ass cylinder head so it's probably due.

Edited August 4, 2014 by Carter Pewterschmidt

[Horri]

Eh, if the guys got a parts motor and the cylinder and piston are actually good, why not swap the two over.  I mean, if it's just sitting there, you might as well make use of it if it's good.  That is, if it's needed.

 

Though I'd get the head rebuilt regardless,  These motors love eating valve guides, can have head warping/cracking, not to mention it's just an old ass cylinder head so it's probably due.

Yep..all well and good in a perfect world..I was just wanting to know if it was an XL engine...Can't just go swapping bores and pistons around on the wrong bits..plus there's no telling if the other engines any good either..